Relative risk ratio: Difference between revisions
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Note that the relative risk ratio is that same as 1 - the [[relative risk reduction]]. | Note that the relative risk ratio is that same as 1 - the [[relative risk reduction]]. | ||
The relative risk ratio may be used to derive the [[number needed to treat]]:<ref name="pmid11914297">{{cite journal |author=Furukawa TA, Guyatt GH, Griffith LE |title=Can we individualize the 'number needed to treat'? An empirical study of summary effect measures in meta-analyses |journal=Int J Epidemiol |volume=31 |issue=1 |pages=72–6 |year=2002 |month=February |pmid=11914297 |doi= |url=http://ije.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=11914297 |issn=}}</ref><ref name="pmid8601116">{{cite journal |author=Chatellier G, Zapletal E, Lemaitre D, Menard J, Degoulet P |title=The number needed to treat: a clinically useful nomogram in its proper context |journal=BMJ |volume=312 |issue=7028 |pages=426–9 |year=1996 |month=February |pmid=8601116 |pmc=2350093 |doi= |url=http://bmj.com/cgi/pmidlookup?view=long&pmid=8601116 |issn=}}</ref> | |||
:<math>NNT = \frac{1}{CER * (1-RRR)} \mbox{, where CER is control event rate and RRR is relative risk ratio}</math> | |||
==References== | ==References== | ||
Revision as of 23:44, 1 March 2009
In clinical epidemiology and evidence-based medicine, the relative risk ratio or more simply the relative risk, is a measure of the likelihood of a clinical outcome in group of patients exposed to a factor compared to a control group of patients.[1] This measure should be contrasted with the absolute risk reduction.
Calculations
| Outcome | ||||
|---|---|---|---|---|
| Present | Absent | |||
| Experimental group | Cell A | Cell B | Total in the experimental group | |
| Control group | Cell C | Cell D | Total in the control group | |
| Total with the outcome | Total without the outcome | |||
Note that the relative risk ratio is that same as 1 - the relative risk reduction.
The relative risk ratio may be used to derive the number needed to treat:[2][3]
References
- ↑ Barratt A, Wyer PC, Hatala R, et al (2004). "Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat". CMAJ 171 (4): 353–8. DOI:10.1503/cmaj.1021197. PMID 15313996. Research Blogging.
- ↑ Furukawa TA, Guyatt GH, Griffith LE (February 2002). "Can we individualize the 'number needed to treat'? An empirical study of summary effect measures in meta-analyses". Int J Epidemiol 31 (1): 72–6. PMID 11914297. [e]
- ↑ Chatellier G, Zapletal E, Lemaitre D, Menard J, Degoulet P (February 1996). "The number needed to treat: a clinically useful nomogram in its proper context". BMJ 312 (7028): 426–9. PMID 8601116. PMC 2350093. [e]